Coaxial needle assembly

ABSTRACT

An adjustable coaxial needle assembly for placement into a tissue mass prior to a biopsy procedure comprises a guide cannula assembly, a stylet, and a throw calibrator. The stylet is selectively coaxially received by the guide cannula, which is in turn coaxially received by the throw calibrator. The effective length of the guide cannula can be selectively adjusted by moving the throw calibrator relative to the guide cannula to adjust the distance between an open distal end of the guide cannula and a the throw calibrator.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.12/173,181, filed Jul. 15, 2008, now U.S. Pat. No. 8,343,072, issuedJan. 1, 2013, which claims the benefit of U.S. Provisional PatentApplication No. 60/949,966, filed Jul. 16, 2007, both of which areincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

In one aspect, the invention relates to a coaxial needle assembly forthe placement of a cannula within a tissue prior to a biopsy procedure.

2. Description of the Related Art

A biopsy is a well-known medical procedure that involves taking a sampleof tissue from a person and examining it for diagnostic purposes. Thebiopsy is often done when an abnormality, such as a lesion, is found ina tissue mass, using an imaging system, such as mammography orultrasonography, or other methods of detection. While biopsies can beused for many different purposes, examining a sample of tissue from anabnormal site is one way to accurately diagnose whether the site iscancerous. In the case of suspected cancer, particularly cancer of thebreast, early detection and diagnosis is critical to the success of thepatient's treatment and recovery.

One biopsy technique frequently performed is a core biopsy, which uses abiopsy device in which a tissue specimen is captured in a coring cannulathat is advanced into the tissue mass to the site of the abnormality.Some biopsy devices use a notched biopsy stylet that is inserted into alesion, such that tissue prolapses into the notch on the biopsy stylet,with the coring cannula then advancing over the notch to cut a tissuesample. Other devices use just a coring cannula, which requires movingthe end of the coring cannula to effect severing of the tissue samplefrom the surrounding tissue mass. Another device advances a spoon intothe tissue mass, which is then followed by a coring cannula having acutting finger, which is rotated to sever the tissue sample. Such adevice can be found in commonly assigned U.S. Patent ApplicationPublication No. 2006/0030785, entitled “Core Biopsy Device”, which isincorporated herein by reference in its entirety. The biopsy cannula andstylet, if used, with the tissue sample, is then removed from thetissue, and the tissue sample is examined.

It is often necessary to take multiple tissue samples from the lesionand/or the surrounding area. To avoid having to puncture the skin forevery tissue sample, a coaxial needle assembly is placed in the tissueprior to use of the biopsy device to act as a guide for the biopsydevice. A coaxial needle assembly commonly includes a needle cannuladefining a lumen in which a stylet is received to close off the opendistal end of the needle cannula during insertion to prevent unwantedcoring of the tissue. After insertion, the stylet is removed and thebiopsy cannula and stylet/spoon of the biopsy device are insertedthrough the needle cannula and into the lesion to take a tissue sample.The biopsy device is then removed from the tissue, and the needlecannula can be manipulated to a new location within the tissue mass sothat upon reinsertion of the biopsy device, a tissue sample can be takenfrom a different area of or surrounding the lesion.

The coaxial needle assembly is commonly placed using an imaging device.The placement normally locates the tip of the needle cannula at thedesired location relative to the lesion. The biopsy device and needlecannula can be configured such that the biopsy device is alignedrelative to the needle cannula to insure that upon actuation of thebiopsy device, the biopsy specimen will be taken at a known distancefrom the tip of the needle cannula. A common way of accomplishing thealignment is to insert the biopsy device into the needle cannula untilthe biopsy device aligns with a reference point on the needle cannula.This can be done by aligning marks on the biopsy device and needlecannula or by inserting the biopsy device until it abuts the needlecannula. In most cases, the tip of the biopsy device's cannula/stylet isaligned with the tip of the needle cannula when the biopsy device andneedle cannula are aligned. The reference points are external of thetissue mass, whereas the tips of the biopsy device and needle cannulaare internal of the tissue mass, which provides the user with anexternally visual method of aligning the internal tips, which are notvisible other than using an imagining device.

The position of the needle cannula determines what tissue will besampled by the biopsy device, since the biopsy cannula will protrudefrom the end of the needle cannula to take a tissue sample. Therefore,for current systems the alignment is dependent on the length of theneedle cannula being the same as or a fixed length relative to thebiopsy cannula prior to taking a tissue sample.

The current alignment approach is not compatible with biopsy deviceshaving adjustable length biopsy specimens, especially those thatincrease the relative length of the cannula or stylet to adjust thelength of the specimen. If the length of the biopsy device's cannula orstylet is extended/retracted relative to the supporting body to effectthe specimen length adjustment and the abutment of the supporting bodywith the needle cannula is used for alignment, the biopsy device'scannula or stylet will be over/under inserted relative to the cannulaneedle. As such, it becomes necessary to account for the difference inlengths between the biopsy cannula and stylet and the needle cannula,which has a fixed length. This is difficult, since the user cannot viewthe position of the cannulas within the body and must rely upon externalcues to verify that the biopsy cannula is correctly positioned withinthe needle cannula.

Another issue is that manufacturers of biopsy devices and coaxial needleassemblies often have unique ways of measuring the length of theirrespective cannulas. It is therefore difficult to use one manufacturer'sbiopsy device with another manufacturer's coaxial needle assembly.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a coaxial needleassembly for use with a biopsy device comprises a cannula defining alumen and having a proximal end and a distal end, a stylet removablyreceived within the lumen and having a proximal end and a distal end,and a throw calibrator adjustably carried by the cannula and having abiopsy device insertion stop, wherein the throw calibrator may be usedto adjust the position of the insertion stop relative to the cannula tocalibrate the coaxial needle assembly with the throw distance of thebiopsy device.

In accordance with another aspect of the invention, a biopsy devicesystem for the percutaneous removal of a specimen from an area ofinterest within a tissue mass is disclosed. The biopsy device systemcomprises a variable throw biopsy device having a needle assembly withan adjustable throw distance, a guide cannula defining a lumen andhaving a proximal end and a distal end, and a throw calibratoradjustably carried by the guide cannula and having a biopsy deviceinsertion stop, wherein the throw calibrator may be used to adjust theposition of the insertion stop relative to the guide cannula tocalibrate the guide cannula with the throw distance of the biopsydevice.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a coaxial needle assembly comprising acannula assembly, a stylet assembly, and a throw calibrator according toa first embodiment of the invention.

FIG. 2 is an exploded view of the coaxial needle assembly from FIG. 1.

FIG. 3 is a close-up cross-sectional view of the cannula assembly fromFIG. 1.

FIG. 4 is a close-up cross-sectional view of the stylet assembly fromFIG. 1.

FIG. 5 is a close-up cross-sectional view of the throw calibrator fromFIG. 1.

FIGS. 6A-6B are cross-sectional views through the coaxial needleassembly from FIG. 1, illustrating the movement of the throw calibratoralong the cannula assembly.

FIG. 7A is a cross-sectional view of the coaxial needle assemblyinserted into a tissue mass having a lesion.

FIG. 7B is a cross-sectional view of the coaxial needle assemblyinserted into the lesion in the tissue mass.

FIG. 7C is a cross-sectional view of the stylet assembly of the coaxialneedle assembly withdrawn from the tissue mass, leaving the cannulaassembly and throw calibrator in place.

FIG. 7D is a cross-sectional view of a biopsy device inserted into thecoaxial needle assembly.

FIG. 8 is a perspective view of a biopsy device system comprising thecoaxial needle assembly from FIG. 1 inserted to the lesion and a biopsydevice comprising a biopsy needle assembly for obtaining a biopsy samplefrom the lesion by inserting the needle assembly through the cannulaassembly.

FIGS. 9A-9B are cross-sectional views through the biopsy device systemfrom FIG. 8, with the coaxial needle assembly received on the biopsydevice to calibrate the coaxial needle assembly with the throw distanceof the biopsy device.

FIG. 10 is a perspective view of a coaxial needle assembly comprising acannula assembly, a stylet assembly, and a throw calibrator according toa second embodiment of the invention.

FIG. 11 is an exploded view of the coaxial needle assembly from FIG. 9.

FIG. 12 is a perspective view of the coaxial needle assembly from FIG. 9with a distal tip protector disposed on the throw calibrator.

FIG. 13A is a close-up perspective view of a luer lock coupling for thecannula assembly and stylet assembly in an uncoupled or unlockedposition.

FIG. 13B is a close-up perspective view of the luer lock coupling in acoupled or locked position.

FIG. 14 is a perspective view of a biopsy device system comprising thecoaxial needle assembly from FIG. 10 inserted to the lesion and a biopsydevice comprising a biopsy needle assembly for obtaining a biopsy samplefrom the lesion by inserting the needle assembly through the cannulaassembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-2, a coaxial needle assembly 10 according to afirst embodiment of the invention is illustrated, and comprises acannula assembly 12, a stylet assembly 14, and an adjustable bodycomprising a throw calibrator 16 that is used to calibrate the coaxialneedle assembly 10 with the throw of a biopsy device. The styletassembly 14 is selectively coaxially received by the cannula assembly12, which is in turn selectively coaxially received by the throwcalibrator 16. As used herein with respect to the coaxial needleassembly 10, the terms “distal” and “forward” refer to or in a directiontoward that end of the coaxial needle assembly 10 that is directedtoward a lesion and away from a user. “Proximal” or “rearward” thusrefers to or in a direction toward that end of the coaxial needleassembly 10 that is directed away from the lesion and toward the user.It is also understood that some of the drawings are not to scale, inorder to clearly illustrate the various features of the invention.

Referring to FIGS. 1-3, the cannula assembly 12 comprises a guidecannula 18 defining a lumen 20 and having an open distal end 22 and anopen proximal end 24. A cannula hub 26 is attached to the outer surfaceof the guide cannula 18 near the open proximal end 24. The cannula hub26 comprises a cylindrical body 28 having a rearward end wall 30 and aforward end wall 32, and a hollow interior 34 extending though thecylindrical body 28 to accommodate the guide cannula 18 and the styletassembly 14.

The cylindrical body 28 includes a proximal section 36 joined to adistal section 38 that is of slightly greater diameter than the proximalsection 36 to form a stylet hub engaging surface 40 that facesrearwardly. A pair of opposing rearward end flanges 42 extend partiallyaround the periphery of the proximal section 36, adjacent the rearwardend wall 30, and a forward end flange 44 extends around the periphery ofthe distal section 38, adjacent the forward end wall 44. A flexibledetent 46 is formed on the forward end flange 44 and projects distallyof the forward end wall 32.

Referring to FIGS. 1-2 and 4, the stylet assembly 14 comprises a needleor stylet 48 having a distal end 50 defining an insertion tip 52 and aproximal end 54. A stylet hub 56 is attached to the stylet 48 near theproximal end 54 and can be releasably coupled with the cannula hub 26.The stylet hub 56 comprises a proximal handle section 58, which a usercan grip to manipulate the stylet assembly 14, joined with a distalreceiving section 60 having a hollow interior 62 which receives theproximal section 36 of the cannula hub 36 and a forward end wall 63. Thehollow interior 62 comprises screw threads 64 that are engaged by therearward end flange 42 by rotating the proximal section 36 within thehollow interior 62 to releasably fasten the stylet assembly 14 to thecannula assembly 12.

Referring to FIGS. 1-2 and 5, the throw calibrator 16 comprisesgenerally cylindrical body that encircles the guide cannula 18 and canslidably move relative to the guide cannula 18. The throw calibrator cancomprise an insertion stop 66 for arresting the insertion of a biopsydevice needle assembly into a tissue mass. By adjusting the position ofthe insertion stop 66 relative to the cannula assembly 12 (in this caseby axially moving the throw calibrator 16), the coaxial needle assembly10 can be calibrated with the throw of a biopsy device.

As illustrated herein, the throw calibrator 16 comprises a proximal orrearward end wall 66 that acts as the insertion stop 66, a distal orforward end wall 68, and a hollow interior 70 extending though the throwcalibrator 16 to accommodate the cannula assembly 12 and the styletassembly 14. The throw calibrator 16 includes a proximal cylindricalsection 72 joined to a distal nose section 74 that has a smallerdiameter than the cylindrical section 72. An elongated slot 76 is formedon the cylindrical section 72 and slidingly receives the detent 46 onthe cannula assembly 12 to prevent the cannula assembly 12 from rotatingwith respect to the throw calibrator 16 and to guide the longitudinalmovement of the cannula assembly 12 relative to the throw calibrator 16.The length of the elongated slot 76 further determines the range ofmovement of the throw calibrator 16 relative to the cannula assembly 12.The length of the elongated slot 76 can selected such that the range ofmovement of the throw calibrator 16 corresponds to the range of possiblethrow distances of a biopsy device.

The hollow interior 70 of the throw calibrator 16 receives a releasablelock that fixes the position of the throw calibrator 16 in relation tothe cannula assembly 12, and, as illustrated herein, includes a torsionspring 78 having spring arms 80 that protrude through an opening 82formed in the nose section 74. When assembled, the guide cannula 18 isslidably received through the torsion spring 78 to releasably fix theposition of the throw calibrator 16 along the guide cannula 18.Squeezing the spring arms 80 releases the torsion spring 78 relative tothe guide cannula 18, permitting the throw calibrator 16 to be slidalong the guide cannula 18 until the spring arms 80 are released.

Referring to FIGS. 6A-6B, the coaxial needle assembly 10 can becalibrated with the throw distance of a biopsy device by moving thethrow calibrator 16 relative to the cannula assembly 12. This adjuststhe effective length of the guide cannula 18, which is the distancebetween the open distal end 22 and the insertion stop 66 of the throwcalibrator 16. This also adjusts the distance the stylet 48 protrudeswith respect to the throw calibrator 16, since the insertion of thestylet 48 within the guide cannula 18 is limited by the abutment of theforward end wall 63 against the stylet hub engaging surface 40. Theeffective length of the guide cannula 18 is adjusted by pressing thespring arms 80 toward each other to expand the torsion spring 78 andloosen its grip on the guide cannula 18, allowing the throw calibrator16 to be translated along the cannula assembly 12. The range of movementof the throw calibrator 16 relative to the cannula assembly 12 islimited by the length of the slot 76 in which the detent 46 moves. Asshown in FIG. 6A, the guide cannula 18 is at a minimum effective lengthin the position where the detent 46 abuts the forward portion of theslot 76. As shown in FIG. 6B, the guide cannula 18 is at a maximumeffective length in the position where the detent 46 abuts the rearwardportion of the slot 76. It is understood that the effective length ofthe guide cannula 18 is infinitely adjustable between the positionsillustrated in FIGS. 6A-6B because the position of the throw calibrator16 is infinitely adjustable. It is also understood that the cannulaassembly 12 and stylet assembly 14 can be moved as a unit, while keepingthe throw calibrator 16 relatively still. The throw calibrator 16, oranother portion of the coaxial needle assembly 10, can further beprovided with indicia (not shown), such as distance markings or adigital display, for enabling the length of coaxial needle assembly 10to be adjusted a predetermined distance.

FIG. 8 illustrates one example of a biopsy device system for thepercutaneous removal of a specimen from an area of interest within atissue mass 100, in which the coaxial needle assembly 10 is used inconjunction with a biopsy device 300. An exemplary biopsy device 300comprises a actuator assembly 302 structurally and operably connected toa biopsy needle assembly 304 which is used to penetrate the tissue mass100 to obtain a biopsy sample from an area of interest comprising alesion 200. The biopsy needle assembly 304 includes a biopsy cannula 306and a biopsy stylet 308 which is received by the biopsy cannula 306 incoaxially telescoping relationship. The biopsy needle assembly 304 has athrow distance, which is the distance the biopsy stylet 306 travelsrelative to the biopsy cannula 306 when fired, and which determines thesize or length of the specimen obtained.

The biopsy device 300 can comprise a variable throw biopsy device havingan adjustable throw distance to permit the user to select the size orlength of the specimen obtained. As illustrated herein, the biopsydevice 300 comprises an adjustable biopsy stylet 308 and a biopsycannula 306 with a fixed extension distance. Since the length of thetissue sample is set by the distance from the tip of the stylet 308 tothe tip of the cannula 306 when the stylet 308 has been fired, thisdistance can be adjusted by extending or retracting the stylet 308.Thus, adjusting the throw of the biopsy device 300 also adjusts the sizeor length of the specimen obtained. Since the guide cannula 18 isadjustable in effective length, it can advantageously accommodate forthe adjusted length of the biopsy stylet 308. In use, the throw distanceof the biopsy stylet 308 is set first, and then the coaxial needleassembly 10 is calibrated with the set length of the biopsy stylet 308.

Referring to FIGS. 9A-9B, one expeditious way of calibrating the coaxialneedle assembly 10 is to insert the assembled cannula assembly 12 andthrow calibrator 16, without the stylet assembly 14, over the biopsyneedle assembly 304 until the actuator assembly 302 abuts the insertionstop 66, as shown in FIG. 9A. The throw calibrator 16 is then adjustedalong the cannula assembly 12 until the distal tip of the biopsy needleassembly 304 and the open distal end 22 of the guide cannula 18 are in asuitable predetermined relationship for insertion into the tissue mass,as shown in FIG. 9B. One suitable predetermined relationship is one inwhich the distal tip of the biopsy stylet 308 being flush with the opendistal end 22 of the guide cannula 18, which makes the effective lengthof the cannula assembly 12 equal to the length of the biopsy stylet 308.Another suitable predetermined relationship is one in which the distaltip of the biopsy cannula 306 being flush with the open distal end 22 ofthe guide cannula 18, which makes the effective length of the cannulaassembly 12 equal to the length of the biopsy cannula 306. Bothrelationships guarantee that the tissue at the end of the guide cannula18 will be sampled. Another suitable predetermined relationship is onein which the distal tip of the biopsy needle assembly 304 closes theopen distal end 22 of the guide cannula 18, which insures that tissuewill not prolapse into the guide cannula 18. The coaxial needle assembly10 is then removed from the biopsy device 200 and the stylet assembly 14is reassembled to the coaxial needle assembly 10, readying it forinsertion in the tissue mass 100.

Another way of calibrating the coaxial needle assembly 10 is to simplydetermine the throw distance of the biopsy device 300 and set theeffective length in accordance with the throw distance using indiciaprovided on the guide cannula. This is especially effective if theindicia directly correlate with the possible throw distances on thebiopsy device 300.

Referring to FIGS. 7A-7C, the coaxial needle assembly 10 is illustratedwithin a tissue mass 100 having a lesion 200 to show the various stepsin the process of placing the coaxial needle assembly 10 at the lesion200 prior to using a biopsy device to obtain a tissue sample from thelesion 200. Prior to insertion, the coaxial needle assembly 10 iscalibrated with the throw distance of the biopsy device as discussedabove by moving the throw calibrator 16 along the guide cannula 18 toset the effective length of the guide cannula 18. As shown in FIG. 7A,the coaxial needle assembly 10 is inserted into the tissue mass 100 withthe stylet assembly 14 coaxially received by and coupled to the cannulaassembly 12, such that the stylet 48 is received within the lumen 20 andprotrudes slightly from the open distal end 22 of the guide cannula 18,with the insertion tip 52 leading the coaxial needle assembly 10 throughthe tissue mass 100.

As shown in FIG. 7B, the coaxial needle assembly 10 is positioned sothat the insertion tip 52 is at or near the lesion 200. Preferably, thecoaxial needle assembly 10 is positioned by using an imaging system. Thecoaxial needle assembly 10 can be designed for enhanced visibility usingcommon imaging systems, such as CAT scan, ultrasonography andmammography. For example, a portion of the coaxial needle assembly 10can be enhanced for ultrasound detection by forming an echogenicityenhancement on either the guide cannula 18 or the stylet 48. Once suchenhancement is disclosed in U.S. Pat. No. 5,820,554 to Davis et al.,incorporated herein by reference in its entirety.

As shown in FIG. 7C, once the coaxial needle assembly 10 is positioned,the stylet assembly 14 is unlocked from the cannula assembly 12 andwithdrawn from the tissue mass 100, thereby removing the stylet assembly14 from rest of the coaxial needle assembly 10. The stylet assembly 14is unlocked by rotating the stylet hub 56 relative to the cannulaassembly 12 to unscrew the rearward end flanges 42 from the screwthreads 64.

Referring to FIG. 7D, after placement of the coaxial needle assembly 10at the lesion 200 and withdrawal of the stylet assembly 14, asillustrated in FIGS. 7A-7C, the biopsy needle assembly 304 is insertedthrough the lumen 20 of the guide cannula 18 until it meets theinsertion stop 66. Since the effective length of the guide cannula 18has been calibrated with the throw distance of the biopsy device 300,the biopsy needle assembly 304 and the guide cannula 18 are in asuitable predetermined relationship; in this case, the tip of the biopsystylet 308 will protrude slightly from the open distal end 22 of theguide cannula 18 into the lesion 200. This is extremely beneficial tothe technician taking the biopsy specimen as one cannot see the locationof the tip of the biopsy device 300 as it is in the tissue mass, butstill knows that the physical relationship between the cannula guide 18and biopsy device 300 will result in the biopsy device 300 beingproperly located. This will negate the need for the technician tore-image the location of the biopsy device 300 after insertion. It willalso simplify the taking of multiple specimens, which requires thewithdrawal and reinsertion of the biopsy device 300.

Referring to FIGS. 10-11, a coaxial needle assembly 10′ according to asecond embodiment of the invention is illustrated, with like elementsbeing identified by like numerals bearing a prime (′) symbol. Thestructure and the method of using the second embodiment is substantiallysimilar to the structure of method of using the first embodiment, so thediscussion of the second embodiment will be limited to the differencesbetween the two embodiments. Whereas the throw calibrator 16 shown inFIGS. 1-2 had a generally uniformly cylindrical proximal section 72, thethrow calibrator 16′ has a protruded area 84 on the proximal section72′, which allows for easier removal of the cannula assembly 14′ fromthe throw calibrator 16′. The elongated slot 76′ is formed on theprotruded area 84. Additionally, indicia comprising a set of distancemarkings 86 is provided on the proximal section 72′ adjacent theelongated slot 76′. The distance markings 86 enable the effective lengthof guide cannula 18′ to be adjusted a predetermined amount, with orwithout the guide cannula 18′ being inserted over a needle assembly of abiopsy device. The distance markings 86 can directly or indirectlycorrespond to the throw of a biopsy device, such that the distancemarkings 86 can be used to calibrate the coaxial needle assembly 10 withthe throw distance of a biopsy device.

The throw calibrator 16′ further comprises at least one rib 88 formed onthe nose section 74 for frictionally engaging a tip protector 90, shownin FIG. 12 which is a sleeve-like device commonly used to cover a needleassembly when not in use, and can be temporarily press fit over the nosesection 74. When the tip protector 90 is received on the nose section74, the spaces between adjacent ribs 88 form passageways 92 throughwhich a sterilization fluid, such as ethylene oxide (EtO) gas, can flowbetween the coaxial needle assembly 10′ and the tip protector 90.

The guide cannula 18 and the stylet 48 are provided with at least onemarker for enhanced visibility using common imaging systems. Asillustrated herein, the guide cannula 18 comprises multiple spacedmarkers on its exterior that are spaced at regular intervals, such asevery 1 cm, and the stylet 48 comprises a marking 96 near or at itsdistal end 50′, which can comprise an echogenicity enhancement asdisclosed in the Davis patent.

Referring to FIGS. 13A-13B, the stylet hub 56′ is coupled with thecannula hub 26′ by a luer lock coupling, which provides a fluid-tightcoupling between the hub 26′, 56′ and allows the user to optionallyinject fluid through the coaxial needle assembly 10′. The distalreceiving section 60′ of the stylet hub 56′ comprises two opposed arms98 which engage the flanges 42′ on the cannula hub 26′ to releasablyfasten the stylet assembly 14′ to the cannula assembly 12′. The styletassembly 14′ is coupled or locked to the cannula assembly 12′ byrotating the stylet hub 26′ relative to the cannula hub 56′ until thearms 98 engage the flanges 42′, as shown in FIG. 13B.

FIG. 14 illustrates one example of a biopsy device system for thepercutaneous removal of a specimen from an area of interest within atissue mass 100, in which the coaxial needle assembly 10′ is used inconjunction with a variable throw biopsy device 400. The exemplaryvariable throw biopsy device 400 comprises a actuator assembly 402structurally and operably connected to a biopsy needle assembly 404which is used to penetrate the tissue mass 100 to obtain a biopsy samplefrom an area of interest comprising a lesion 200. The biopsy needleassembly 404 includes a biopsy cannula 406 and a biopsy stylet 408 whichis received by the biopsy cannula 406 in coaxially telescopingrelationship. The biopsy needle assembly 404 has an adjustable throwdistance, which is the distance the biopsy stylet 406 travels relativeto the biopsy cannula 406, to permit the user to select the size orlength of the specimen obtained. Examples of a suitable variable throwbiopsy device are disclosed in U.S. Pat. No. 8,197,419, issued Jun. 12,2012, and its priority document, U.S. Provisional Application No.61/057,378, filed May 30, 2008, both of which are incorporated herein byreference in their entirety, in which the position of a throw stop (notshown) is adjusted to set the throw distance, i.e. the distance thebiopsy stylet 406 can travel when fired. Another example of a suitablevariable throw biopsy device is disclosed in U.S. patent applicationSer. No. 10/908,427, filed May 11, 2005, now U.S. Pat. No. 8,088,081,issued Jan. 3, 2012, which is incorporated herein in its entirety.

It is understood that the coaxial needle assembly 10, 10′ of theinvention could be used with a biopsy device having a coring cannula anda non-notched stylet. In such a variation, the throw distance of thecore biopsy device would be the distance the coring cannula travels pastthe stylet. The throw distance would be roughly equal to the distancethe distal edge of the coring cannula projects past the distal tip ofthe stylet when fired.

The adjustable coaxial needle assembly 10 allows the user to adjust thelocation of the throw calibrator 16 along the cannula assembly 12 andmaintain a predetermined correct relationship between the cannula andstylet distal ends 22, 50 that is suitable for insertion of the coaxialneedle assembly 10 into a tissue mass. One example of a relationshipsuitable for insertion of the coaxial needle assembly 10 into a tissuemass is one in which the distal end 50 or insertion tip 52 of the styletassembly 12 closes the open distal end 22 of the cannula assembly 12 toprevent tissue from entering the lumen 20. The ability to adjust theeffective length of the cannula assembly and maintain a correctpredetermined relationship between the stylet and cannula ends isdesirable because the coaxial needle assembly 10 can accommodate themoving stylet of a variably throw biopsy device, insuring that a correctsample size is obtained. The coaxial needle assembly 10 can also be usedwith non-variable throw biopsy devices, and has the advantage of beingusable with a variety of biopsy devices having different throwdistances.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation, and the scope of theappended claims should be construed as broadly as the prior art willpermit.

What is claimed is:
 1. A coaxial needle assembly for use with a variable throw biopsy device having a needle assembly comprising a biopsy cannula and a biopsy stylet which is received by the biopsy cannula in coaxially telescoping relationship and a throw distance comprising the distance the biopsy stylet travel relative to the biopsy cannula when the biopsy device is fired, the coaxial needle assembly comprising: a cannula defining a lumen adapted to receive the needle assembly of the biopsy device and having a proximal end and a distal end; a stylet removably received within the lumen and having a proximal end and a distal end; and a throw calibrator adjustably carried by the cannula and having a proximal end and a distal end, the proximal end and defining a biopsy insertion stop adapted to arrest the insertion of the needle assembly into a tissue mass by abutting a portion of the biopsy device against the insertion stop; wherein the throw calibrator may be used to adjust the position of the insertion stop relative to the cannula to calibrate the coaxial needle assembly with the throw distance of the biopsy device.
 2. The coaxial needle assembly according to claim 1 wherein the throw calibrator comprises an elongated slot and the cannula has a detent that is received in the slot to permit relative longitudinal movement between the throw calibrator and the cannula, whereby the length of the elongated slot determines the range of movement of the throw calibrator relative to the cannula.
 3. The coaxial needle assembly according to claim 2 wherein the length of the elongated slot is selected such that the range of movement of the throw calibrator relative to the cannula corresponds to the range of possible throw distances of the biopsy device.
 4. The coaxial needle assembly according to claim 1 wherein the throw calibrator further comprises a releasable lock to releasbly fix the position of the insertion stop along the cannula.
 5. The coaxial needle assembly according to claim 4 wherein the releasable lock comprises a torsion spring carried by the throw calibrator and encircling the cannula.
 6. The coaxial needle assembly according to claim 1 wherein the throw calibrator comprises a cylindrical body that encircles the cannula and slidably moves relative to the cannula, the cylindrical body comprising the proximal and distal ends of the throw calibrator.
 7. The coaxial needle assembly according to claim 6 wherein the slidable adjustment of the cylindrical body adjusts the effective length between the proximal end defining the insertion stop and the distal end of the cannula.
 8. The coaxial needle assembly according to claim 7 wherein the cylindrical body comprises indicia that correspond to the throw distance of the biopsy device such that the indicia can be used to calibrate the coaxial needle assembly with the throw distance of the biopsy device.
 9. The coaxial needle assembly according to claim 1 wherein the cannula further comprises a cannula hub attached to the proximal end of the cannula and the stylet further comprises a stylet hub attached to the proximal end of the stylet and the stylet hub is releasably coupled with the cannula hub.
 10. The coaxial needle assembly according to claim 9 wherein the stylet hub and the cannula hub are releasably coupled by a luer lock coupling.
 11. The coaxial needle assembly according to claim 1 wherein the throw calibrator is infinitely adjustable between a minimum effective length and a maximum effective length, wherein the effective length is the distance between the distal end of the cannula and the insertion stop.
 12. The coaxial needle assembly according to claim 1 wherein the throw calibrator comprises indicia that correspond to the throw distance of the biopsy device such that the indicia can be used to calibrate the coaxial needle assembly with the throw distance of a biopsy device.
 13. A biopsy device system for the percutaneous removal of a specimen from an area of interest within a tissue mass, the biopsy device system comprising: a variable throw biopsy device having a needle assembly with an adjustable throw distance, the needle assembly comprising a biopsy cannula and a biopsy stylet which is received by the biopsy cannula in coaxially telescoping relationship and the throw distance comprising the distance the biopsy stylet travels relative to the biopsy cannula when the biopsy device is fired; a guide cannula defining a lumen configured to receive the needle assembly and having a proximal end and a distal end; and a throw calibrator adjustably carried by the guide cannula and having a biopsy device insertion stop configured to arrest the insertion of the needle assembly into a tissue mass by abutting a portion of the biopsy device against the insertion stop; wherein the throw calibrator may be used to adjust the position of the insertion stop relative to the guide cannula to calibrate the guide cannula with the throw distance of the biopsy device.
 14. The biopsy device system according to claim 13 and further comprising a tip protector defining a lumen, wherein the tip protector is removably received on the guide cannula with the guide cannula extending through the lumen of the tip protector.
 15. The biopsy device system according to claim 14 and further comprising at least one passageway for the flow of sterilization fluid between the tip protector and the guide cannula.
 16. The biopsy device system according to claim 13 and further comprising a stylet removably received within the lumen and having a proximal end and a distal end, wherein the stylet and the guide cannula together form a coaxial needle assembly when the stylet is received within the lumen.
 17. The biopsy device system according to claim 16 wherein the guide cannula further comprises a cannula hub attached to the proximal end of the cannula and the stylet further comprises a stylet hub attached to the proximal end of the stylet and the stylet hub is releasably coupled with the cannula hub.
 18. The biopsy device system according to claim 13 wherein the position of the insertion stop relative to the distal end calibrates the effective length of the guide cannula with the throw distance of the biopsy device.
 19. The biopsy device system according to claim 18 wherein the range of movement of the insertion stop relative to the cannula corresponds to the range of possible throw distances of the biopsy device. 